The invention relates generally to an open end friction spinning machine with a plurality of adjacently arranged yarn formation zones or positions, each of which respectively includes two adjacently arranged rollers driven in the same direction forming a wedge shaped gap. At least one roller, the roller rotating outwardly from the wedge shaped gap, exhibits a continuous or closed cover surface. For conditioning the outer surface of the rollers with closed cover surfaces, there are one or more devices provided, as disclosed in German Patent Application No. P33 36 591.1.
In the above-mentioned disclosure, it is proposed that the spinning conditions and therewith the quality of the spun yarn are maintained constant through the conditioning of the roller with the closed cover surface so as to assure uniform friction characteristics.
One objective of the present invention is to further improve the maintenance of the friction cnaracteristics of the roller, especially rollers with closed cover surfaces, in a constant condition.
This objective is achieved according to the present invention by the provision of one or more devices for monitoring the friction characteristics of at least the rollers with closed cover surfaces.
With this arrangement it is possible to determine the appropriate point in time for conditioning the rollers as necessitated by the actual spinning conditions and also to conduct or monitor conditioning of the rollers in accordance with the desired results.
If a continuous monitoring of the individual spinning positions is to be performed, it is provided in one embodiment of the invention that each spinning position is provided with a device to monitor the friction characteristics of at least the one roller exhibiting a closed covered surface. The devices for monitoring the friction characteristics are connected with a signal sending means for signalling when a respective spinning position is in need of service. Through this signal sending means, a movable servicing apparatus can be activated by means of which conditioning at the corresponding spinning position is carried out.
In order to reduce expenses for the open end friction spinning machine, it is provided, in especially advantageous arrangements of the invention, that the devices for monitoring the friction characteristics are components of a servicing device which is movable along the open end friction machine and adjustably arranged at individual spinning positions. It is advantageous in this arrangement if the servicing device is provided with the device or devices for conditioning. It is then possible, after predetermined time intervals, or on the basis of monitoring spun yarn quality, or after a thread break, to activate the servicing device. The servicing device first monitors the friction characteristics of the roller and thereafter carries out conditioning in dependence upon the measured friction characteristic of the roller.
In further aspects of the invention it is provided that the devices for monitoring the friction characteristics include a device for monitoring the roller which is adjustably movable against the closed cover surface of one roller of the roller pair at a spinning position. The monitoring device is connected with a measuring device for measuring the friction characteristics of the rollers. With the monitoring roller the friction effect of the corresponding roller is directly monitored. In order that this monitoring need not be carried out at too high a driving speed of the rollers, sucn as that which occurs in normal operations, it is provided, in especially advantageous arrangements, that the devices for monitoring the friction characteristics are arranged along with an auxiliary drive at the surface of the roller exhibiting the closed covered surface. The monitoring of the friction characteristics can then be carried out at a roller rotational speed which is suitable for the monitoring operation.
Although the invention has been described and illustrated in detail, it is to be clearly understood that the above is to be taken by way of illustration and example only and not by way of limitation. The spirit and scope of the invention are to be limited only by the terms of the appended claims.